1. Field of the Invention
This invention relates to an improved process for producing pumpable phosphate rock slurries by reducing water content and/or viscosity of phosphate rock slurries used in the manufacture of phosphoric acid.
2. Description of Prior Art
In the manufacture of phosphoric acid from phosphate rock, a slurry of the rock is ground and pumped through pipes during processing. It is desirable to process the rock as a slurry containing a fixed amount of moisture so that sulfuric acid can be added continuously to the slurry at a uniform predetermined rate. When low grade, poor quality, clay bearing phosphate rock is used, viscosity of the slurry varies. It may be necessary to add moisture (water) to dilute the solids content of the slurry thereby reducing the viscosity of the slurry so that the slurry remains pumpable during the process. However, addition of moisture to the slurry not only reduces the production rate but also requires changes in the sulfuric acid addition rate.
U.S. Pat. No. 114,693--Lewis, issued May 9, 1871 describes grinding of phosphatic materials in the presence of water.
U.S. Pat. No. 1,607,666--de Haen issued Nov. 23, 1926 mentions that sodium naphthensulphonate is not a satisfactory peptizing agent.
There is a definite need for improvements in the manufacture of phosphoric acid by the wet process. These improvements include steps to minimize the moisture content of the slurry, to increase the production rate, to increase fluidity of the slurry, to improve pumpability of the slurry, to increase phosphoric acid yields, to reduce pump wear caused by the high solids slurry and to decrease slurry viscosities.